Spark plug



Aug- 5! 1,so3,643 I A. DE CLAIRMONT SPARK PLUG Filed March 5. 1921Parental Aug. s, 1924.

UNITED s'rAT'Es.

Anotro DE cLAmMoN'r, or rotmo, emo.

SPARK PLUG.

Application flled March 5, '1921.

To all whom it may concern: i

Be it known that I, ADoLro Dr. CLAIRMoN'r, citizen of the' UnitedStates, residing at Toledo, in the county of Lucas -and State of Ohio,have invented certain new and useful Improvements in Spark Plugs, ofwhich the following is a specification.

This invention relates toan improved spark plug for internal combustionengines andv has as one of its principal objects to vprovide a device ofthis character wherein a condenser will be interposed between the mainand ground electrodes of the plug to form primary and secondary sparkgaps.

The invention has as afurther object to provide a plug -wherein thecondenser will be formed by a sphericalelectrode so mounted that aprimary spark gap will be provided within the shell of the plug at theupper side of said electrodefwhile secondary spark gaps Will be providedexteriorly of the shell at the lower side of the electrode.

A further object of the invention is to provide a plug whereinthecondenser will be suspended from the insulator ofthe plug and Whereinthe supporting member for said condenser will be so formed andmounted'as to parallel the main electrode employed so that currentflowing through the main -electrode' Will set up induced currents insaid member for surcharging the condenser;

And the invention has as a still further object to provide a plugwherein the condenser as Well as the electrodes of the plug ma bereadilyL cleaned.

ther and incidental objects will appear hereinafter.

In the drawing:

Figure 1 is a vertical sectional view takenl medially through myimproved plug,1

Fig. 2 isI a detail section Vparticularly showing the mounting-of thecondenser of the plug,

Figure 3 is a fragmentary vertical sec-' Vtional view illustrating aslight modification of the invention, and

Figure 4 is ai fragmentary vertical sectional view showing a furthermodified structure.

In carrying the invention into efi'ect, I

employ a shelllO, the lower end portion of.

which is externally threaded forl engagement 'in the usual spark plugorifice of an engine cylinder. Formed within the shell is an annularbeveled shoulder upon which is arranged a suitable gasket 11 and SerialNo. 449,965.

seating against said gasket is an insulator 12 of porcelain or otherapproved material. Surrounding the' insulator is a second gasket 13 ofapproved character and, as will now be observed, the shell is formed atits upper end with a reduced flange or neck 14. which is turned inwardlyto coact with said gasket for tightly connecting the insulator with theShell. Surrounding the upper end portion of the insulator above saidflange is a protecting sleeve 16 beneath which is arranged a suitablesealing gasket 17 resting upon the flange and overlying said sleeve atits upper end is a similar gasket 18. The sleeve 16 may be formed of anyapproved material and is designed to protect the projecting upper endportion of the insulator against accidental injury. Extending axiallythrough the insulator is a main electrode 19 provided near its upper endWith a cylindrical boss or enlargement 20 having threaded engagementwith the insulator and rising from said enlargement is a stud 21 of'adiameter somewhat greater than the diameter of the lower end portion ofthe electrode. Threaded upon said stud to coact With the porcelain is alock nut 22 and threaded upon the stud to overlie said nut is a cap 23cupped to accommodate the nut and seating against the gasket 18- forholding the sleeve 16 in position. Above the cap 23, the stud carries abinding nut 24.

The lower end portion of the insulator, below the body thereof, istapered longitudinally While the main electrode 19 projects below theinsulator and suspended from the insulator to coact With said electrodeis a spherical condenser 25. -This condenser is sustained by asubstantially U-shaped supporting member having parallel sides 26 joinedby a straight connecting portion 27 and, as will be observed uponreference to Figure' 2, the condenser is provided with an eccentricopening therethrough to receive the connecting portion of said memberWhile at the ends of said opening are appropriate notches accommodatingthe sides of the member. The condenser will thus be held againstmovement longitudnally of the connecting portion of the member and willalso be looked against rotation. The sides of the member are arranged tostraddle the main electrode 19 and are embedded in the insulatorextending substantially parallel to sulator. The supporting member willthus be securely joined to the insulator without weakening saidinsulator and, as will now be observed, the member is arranged to sup-'denser. However, the condenser is disposed to project below the lowerend of the shell, the equatorial lane of the condenser being disposedslight above the plane of the lower end edge o the shell and set intothe shell at its lower end to cooperate with said condenser arediametrically arranged ground electrodes 28 providing secondary spark gas between the lower side of the condenser an said electrodes exteriorlyof the shell.

In operation, current flowing through the -main electrode will firstjump to the condenser to provide a spark at the primary gap between saidelectrode and the condenser. From the condenser, the'current'will thenjump to either or both of the ground electrodes to form Sparks at thesecondary gaps of the plug, the interposition of the condenserbetweenthe main and ground electrodes Operating, as will be well understood, togreatly intensify the Sparks given off at the secondary gaps. Further,as will also be readil yappreciated, flow of current through t e main4electrode will set up induced currents in the sides 26 of thesupporting member for the condenser and these induced currents will tendto surcharge the condenser for further increasing the intensity of theSparks given ofl' at the secondary aps. These gaps are located below theower end of the shell so .that when the plug is connected with an enginecylinder, said aps may be entirely exposed within the com ustion chamberof the cylinder. However, fuel gases within said chamber will, ofcourse, rise within the'shell so that the spark produced at the primarygap will also serve its function in igniting said gases. Preferably, thelower end of the insulator termin'ates substantially midway between thebeveled internal shoulder of the shell and the lower end of the shell sothat a considerable space between the lower end of the insulator and thecondenser -is thus defined. A brush or cloth may 'accordingly be easilyforced into the lower end of the shell for cleanin the lower endportion' of the main electro e as well as also cleaning the condenser.Further, by this 'arrangemang a pocket of considerable size is rovidedwithin the lower end portion of t e shell forreceiving fuel gases tocirculate around the primary spark gapnof the plug.A I

Figure 3 of the draw'ing, 'I have illustrated a slight modification oftheinvention wherein the insulator, *indicated at' 29, is removablyfitted'within the shell, the shell beying indicated at 30. The parts 29and 30 correspond, of course, to similar parts of the referredconstruction and surrounding the insulator is a gasket 31 correspondingto the gasket 13. Threaded into the shell to'coact with'said gasket 'isa nut 32 binding the insulator within the shell and, as will beperceived, this nut may be removed for freeing4 the insulator.Otherwise, this modification is identical With the preferred form of theinvention.

In Figure-4, I have illustrated a still further modification. In this'fiure, the shell is indicated: at 33. Embedde in the lower end portion ofthe insulator, as in the preferred construction, are spaced rods 34extending in parallel relation to the main' elsetrode 35 and jointlyproviding the sides of a supporting member for ai condenser 36. Thiscondenser is in the natureof a disc and preferably, the rods arethreadedinto said disc for securing the disc thereon. The coni denser 36corresponds, of course, to the condenser 25 of'the preferredconstruction butv is, however, mounted in. spaced relation to the lowerend of'the Shell so that the entire surface of the condenser disc isexposed below the Shell. In conformity with this arrangement, the mainelectrode35 is elongated to project below the shell so as to co-yoperate with the condenser. Otherwise this modification is identicalwith the preferred construction. i

v Havingthus described the invention, what is elaimed as new is: i

1. A spark plug including a shell, an insulator carried thereby, a mainelectrode extending through the insulator, a spherical condensersuspended from the insulator below the lower end of said electrodeinalinement therewith to intersect the plane ofthe lower end of the shell,the equatorial-plane of the condenser being dis osed above said firstmentioned lane, an a ground electrode upon the sllfell, to cooperatewithsaid condenser... v

2. In'a spark plug, the combination of a shell, an insulator carriedthereby, a main electrode extending through the insulator, a

'spherical condenser spaced below the lower end of said electrode to.form a spark gap between the electrode and the condenser, and asubstantially U-shaped supporting member havin sides embedded at theirfree end portions in the insulator to straddle the main electrode andjoinedb acOnnecting portion extending through said condenser supportingthe condenser, thecondenser having notches therein accommodating thesides of said supporting memberl whereby the condenser 1s held againstrotation as well as movement along said Lconnecting portion to preventthe length of the gap being varied.

3. In a spark plug, .the combination of a shell, an insulator carriedthereby terminatlUlI d of the Shell to deshell below the inextendingthrough g Within the shell operate therewith, a. supporting membersuspending the cond and provided with tions paralleling the exposedenser from the insulator sides having exposed por- 'lower end portion ofthe electrode at opposite sides thereof Within said pocket, the spacebetween the exposed portions of said sides and the exposed portion ofsaid eleetrode being unobstructed, and a ground electrode upon the shellarranged to c'ooperate with said condenser.

In testimony Whereof I aflix my signature.

ADOLFO de CLAIRMONT, IW. D. [L. s.]

